1. Field of the Invention
This invention is directed to improvements in a food cooking apparatus in general and more specifically to improvements in a rotisserie-type cooking apparatus having at least one rotatable element for supporting a food product.
2. Background of the Prior Art
Use of a rotatable element to support a food product for cooking is well known. Such rotatable elements are often referred to as rotisseries, spits, skewers and a host of other names. For simplicity the term rotisserie will be used with the understanding that this term is intended to cover all forms of rotatable elements which support food products or to which food products may be attached for cooking in all types of cooking environments including gas or electric ovens, barbecues, microwave ovens and a variety of other cooking environments.
With reference to FIGS. 1 and 2, there is shown a prior art rotisserie oven disclosed in U.S. Pat. No. 4,561,348 to Halters et al. The oven includes a casing 1 housing a grilling space 2. The grilling space is defined by a plurality of stainless steel walls 5 within outer casing 1. An air flow path is formed between the stainless steel walls 5 and casing 1. Within the air flow path is a motor 10 for a fan and a motor 4 for rotating a spit 3 on which the food is positioned in the grilling space 2. Fan blades 16, which are drivingly connected to motor 10, draw ambient air into the air flow path through apertures 17 and expel air out of the air flow path through apertures 18. The ambient air flowing through the air flow path cools the outer surface of the walls 5.
A fat collecting tray 7 is arranged below spit 3. An upper plate 8 is provided at the top of the cooking chamber. An inner space 2' is formed between the upper plate 8 and the top wall 5' of the cooking chamber. A fan 11 is provided within the inner space 2', and a suction opening 9 in the upper plate 8 permits air from the grilling space 2 to be drawn in the inner space 2'. Several heating elements are provided in the grilling space at 13, 19, 20. A grease collection device includes guide baffles 21 which divert the dripping fat to fat collecting tray 7 through drain hole 22. During cooking, air is drawn into inner space 2' through suction opening 9, expelled downwardly out of inner space 2' through exhaust aperture 12, and diverted by guide baffles 21 upwardly towards suction opening 9. Thus, a circular flow path as shown by the arrows 14 is established within the cooking chamber 2.
In general, the hottest portions of the oven are the portions proximate to the heating elements. In ovens without forced air, a temperature gradient is created whereby the temperature is the highest at the top of the cooking chamber. Even with forced air, though, experience has shown that temperature gradients are formed towards the top of the cooking chamber. In U.S. Pat. No. 4,561,348, the fan motor 10 is disposed above the hot grilling space 2. Consequently, an additional cooling apparatus must be provided. In particular, the '348 patent provides a cooling flow channel extending around the outside of the grilling space 2. The necessity for such an additional cooling apparatus is likely obviated, however, if the temperature sensitive components such as fan motors are relocated.
In addition, in prior art rotisserie ovens in general and in the '348 rotisserie oven in particular, a cylindrical envelope can be defined by the rotatable spit. More particularly, at one end of the rotatable spit 3, a first drum is fixedly mounted thereon and at the other end of the rotatable spit 3, a second drum is fixedly mounted thereon. A cylindrical envelope can be defined between these drums within the cooking chamber. The air within the grilling space 2 is generally directed in a circular path which is tangential to the cylindrical envelope. However, none of the heated air is directed to the inside of the cylindrical envelope. When arranged on the spits, the food has an outer portion aligned on the outside of the cylindrical envelope and an inner portion aligned on the inside of the cylindrical envelope. Since the air is directed generally tangential to the cylindrical envelope, the surface of the food product within the cylindrical envelope is often insufficiently cooked.
Moreover, the grease collection tray disclosed in U.S. Pat. No. 4,561,348 and other prior art ovens are generally shallow, wide drawers disposed beneath the cooking chamber. When emptying the drawer, the operator physically carries the drawer, usually supporting it from below. Since the drawer is shallow, the operator must carefully balance it so that the oil contained therein does not spill while in transit. Thus, grease collection drawers according to the prior art are generally too shallow for safe disposal of the grease. Moreover, since the operator generally grasps the grease collection drawer from the bottom, which is in direct contact with the hot oil, there is a possibility of operator injury.
In addition, in the Halters et al. '348 oven, the inlet opening for the fan 11 sucks air upwardly. While a wire screen might reduce the amount of dripping grease sucked into the inlet opening 9, the screen can become clogged in operation. Therefore, it is desirable to provide a method of reducing the amount of dripping grease and deposits that are directed to the inlet of fans or blowers provided in ovens.
Still further, prior art ovens provide temperature sensors that sense the temperature of the cooking chamber. However, these sensors are often located in the cooking chamber at positions which do not provide the most accurate indication of the average lowest temperature of the cooking chamber. For example, a temperature sensor disposed at the top of the cooking chamber is generally exposed to the hottest air within the cooking space. Consequently, after the oven door is opened, the time that it takes the top of the cooking chamber to drop below the target cooking temperature is generally greater than the time that it takes the bottom of the cooking chamber to drop below the target cooking temperature. Therefore, for a faster temperature recovery upon opening of the oven door, the temperature sensor should be positioned where the lowest average cooking temperature may be read.
Furthermore, prior art ovens often employ radiant heaters to provide surface browning of the food product. By superficially scorching the surface of the food product, the outer skin locks the juices in. If quartz radiant heaters are used for surface browning, an incidental effect is to provide illumination to the interior of the cooking space. Quartz heaters generally operate at extremely hot temperatures, for example 1500.degree. F., and are usually positioned along one of the walls of the cooking chamber. When so disposed, a concentration of heat is conducted to the walls surrounding the quartz heaters. Thus, insulation must be provided along the outer walls of the cooking chamber to isolate the walls exposed to the relatively intense heat generated by the quartz heaters. However, the necessity for additional outer insulation also increases the size of the oven.
In addition, during cooking, juices are released from the food product. These juices raise the relative humidity within the cooking chamber. With the humidity raised, it becomes difficult to scorch the surface of the food product and thereby lock the juices therewithin. Instead, a large portion of the juices flow out of the food product with the consequence that the food is often too dry. It is desirable, therefore, to provide a device for controlling the relative humidity within the cooking chamber so that superficial food surface scorching can be effectively accomplished.
Also, in some cooking applications, it is preferable to direct the forced heated air away from the tray on which the fat and grease are collected. In Halters et al., the grease and fat are collected initially on guide baffles 21. According to the air flow scheme in Halters et al., the forced heated air flows downwardly through the cooking chamber and is diverted upwardly by guide baffles 21 on which dripping grease and fat have accumulated. If high cooking temperatures are employed, the forced heated air in Halters et al. could cause the grease and fat on guide baffles 21 to burn and consequently smoke. Thus, under some rotisserie oven applications implementing relatively high forced air temperatures, it is desirable to control the air flow such that the grease collection device is not directly exposed to the forced heated air.
In order to overcome these and additional disadvantages of prior art rotisseries, the rotisserie oven according to the preferred embodiment has redesigned and repositioned several of the integral components of the oven.